Programmable highly temperature and supply independent oscillator

a high temperature and supply independent, oscillator technology, applied in the direction of oscillator, pulse generator, pulse technique, etc., can solve the problems of high cost and size burden on the sub-system or module, crystal oscillator or tank circuit that is commonly used to generate the reference frequency occupying additional board space, and can be expensive, and internal generated reference frequency, however, tend to be less accurate than their external counterparts, so as to achieve stable and accurate reference frequency

Inactive Publication Date: 2000-12-05
EXAR CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a fully integrated, temperature and supply independent oscillator circuit that provides a stable and accurate reference frequency. Broadly, the circuit of the present invention uses a relaxation type oscillator that operates by supplying a charge current to a capacitor that is charged and discharged based on the level of a threshold voltage. The invention further includes circuitry that generates the charge current and the threshold

Problems solved by technology

In those applications, such as ATM and SONET, that require reference frequencies of 35 Mhz or higher, generating a stable reference signal at such high references places a high cost and size burden on the sub-system or module.
Crystal oscillators or tank circuits that are commonly used to generate the reference frequency take up additional board space a

Method used

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  • Programmable highly temperature and supply independent oscillator
  • Programmable highly temperature and supply independent oscillator
  • Programmable highly temperature and supply independent oscillator

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Embodiment Construction

Referring to FIG. 1, there is shown a simplified block diagram of the oscillator circuit according to one embodiment of the present invention. The oscillator circuit includes a relaxation oscillator 100 that has a charge current I(ch) input, a threshold voltage Vth input and a frequency output FRQ.sub.-- OUT. The VCO further includes a current generating circuit 102 that receives a current output I(bg) of a band-gap circuit 104 and generates a current output I(ch) for the charge current input of relaxation oscillator 100. A voltage generating circuit 106 receives a voltage output V(bg) of band-gap circuit 104 and generates a voltage Vth for the threshold voltage input of relaxation oscillator 100. The band-gap voltage output V(bg) is substantially power supply and temperature independent, while its current output I(bg) varies with temperature. With the output frequency (FRQ.sub.-- OUT) of relaxation oscillator 100 being proportional to the ratio I(ch) / Vth, current and voltage genera...

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PUM

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Abstract

An oscillator circuit generates an output frequency that is substantially independent of power supply and temperature variations. The oscillator circuit can be implemented using conventional complementary metal-oxide-semiconductor technology. The oscillator circuit is suitable for use as an internal oscillator for generating a stable reference frequency in telecommunication receiver modules.

Description

BACKGROUND OF THE INVENTIONThe present invention relates in general to integrated circuits, and in particular to a robust oscillator circuit that is insensitive to variations in temperature and power supply voltage level.In various types of telecommunication systems a reference frequency is commonly used as an acquisition aid in the receiver module. In those applications, such as ATM and SONET, that require reference frequencies of 35 Mhz or higher, generating a stable reference signal at such high references places a high cost and size burden on the sub-system or module. Crystal oscillators or tank circuits that are commonly used to generate the reference frequency take up additional board space and can be expensive. Thus, a receiver that does not require an externally generated reference frequency is very desirable. Internally generated reference frequencies, however, tend to be less accurate than their external counterparts. This is because on-chip oscillator circuitry is more su...

Claims

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Application Information

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IPC IPC(8): H03K3/011H03K3/0231H03K3/00
CPCH03K3/0231H03K3/011
Inventor TSO, VINCENT WING SING
Owner EXAR CORP
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